[ARM] Simplify the creation of escaped build attribute values

[vhscampos]

Summary

There is an existing mechanism to escape strings, therefore the
functions created to escape Tag_also_compatible_with values are not
really needed. We can simply use the pre-existing utilities.

[pratlucas]

LGTM.

llvm/include/llvm/Support/ARMBuildAttributes.h

enum {
   BTINotUsed = 0,
   BTIUsed = 1,
 
   // Tag_PACRET_use, (=76), uleb128
   PACRETNotUsed = 0,
   PACRETUsed = 1
 };
 
-std::string encodeAttrTagValuePair(StringRef OriginalString);
-
 } // namespace ARMBuildAttrs
 } // namespace llvm
 
 #endif

llvm/lib/Support/ARMBuildAttrs.cpp

static const TagNameItem tagData[] = {
     {ARMBuildAttrs::FP_HP_extension, "Tag_VFP_HP_extension"},
     {ARMBuildAttrs::ABI_align_needed, "Tag_ABI_align8_needed"},
     {ARMBuildAttrs::ABI_align_preserved, "Tag_ABI_align8_preserved"},
 };
 
 constexpr TagNameMap ARMAttributeTags{tagData};
 const TagNameMap &llvm::ARMBuildAttrs::getARMAttributeTags() {
   return ARMAttributeTags;
-}
-
-static std::string getEncodedULEB128AsText(const uint8_t *Value,
-                                           unsigned Size) {
-  std::stringstream SS;
-  for (unsigned i = 0; i < Size; ++i) {
-    SS << "\\" << std::setfill('0') << std::setw(3) << std::oct
-       << int(Value[i]);
-  }
-  return SS.str();
-}
-
-std::string
-llvm::ARMBuildAttrs::encodeAttrTagValuePair(StringRef OriginalString) {
-  auto BytesBegin = reinterpret_cast<const uint8_t *>(OriginalString.data());
-  auto BytesEnd = BytesBegin + OriginalString.size();
-
-  unsigned N = 0;
-  const char *Error = nullptr;
-  unsigned Tag = decodeULEB128(BytesBegin, &N, BytesEnd, &Error);
-  if (Error)
-    report_fatal_error("Could not decode Tag value: " + Twine(Error));
-
-  std::string EncodedPair = getEncodedULEB128AsText(BytesBegin, N);
-  switch (Tag) {
-  case ARMBuildAttrs::CPU_raw_name:
-  case ARMBuildAttrs::CPU_name:
-  case ARMBuildAttrs::compatibility:
-  case ARMBuildAttrs::conformance:
-    EncodedPair += OriginalString.substr(N);
-    break;
-  default:
-    EncodedPair +=
-        getEncodedULEB128AsText(BytesBegin + N, OriginalString.size() - N);
-  }
-  return EncodedPair;
-}
+}

llvm/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp

void ARMTargetAsmStreamer::emitTextAttribute(unsigned Attribute,
                                              StringRef String) {
   switch (Attribute) {
   case ARMBuildAttrs::CPU_name:
     OS << "\t.cpu\t" << String.lower();
     break;
   default:
     OS << "\t.eabi_attribute\t" << Attribute << ", \"";
     if (Attribute == ARMBuildAttrs::also_compatible_with)
-      OS << ARMBuildAttrs::encodeAttrTagValuePair(String);
+      OS.write_escaped(String);
     else
       OS << String;
     OS << "\"";
     if (IsVerboseAsm) {
       StringRef Name = ELFAttrs::attrTypeAsString(
           Attribute, ARMBuildAttrs::getARMAttributeTags());
       if (!Name.empty())
         OS << "\t@ " << Name;